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* [PATCH 1/2] ipmr: Fix RCU list debugging warning
@ 2020-02-22  6:38 Amol Grover
  2020-02-22  6:38 ` [PATCH 2/2] ipmr: Add lockdep expression to ipmr_for_each_table macro Amol Grover
  0 siblings, 1 reply; 4+ messages in thread
From: Amol Grover @ 2020-02-22  6:38 UTC (permalink / raw)
  To: David S . Miller, Alexey Kuznetsov, Hideaki YOSHIFUJI, Jakub Kicinski
  Cc: netdev, linux-kernel, linux-kernel-mentees, Joel Fernandes,
	Madhuparna Bhowmik, Paul E . McKenney, Amol Grover

ipmr_for_each_table() macro uses list_for_each_entry_rcu()
for traversing outside of an RCU read side critical section
but under the protection of rtnl_mutex. Hence, add the
corresponding lockdep expression to silence the following
false-positive warning at boot:

[    4.319347] =============================
[    4.319349] WARNING: suspicious RCU usage
[    4.319351] 5.5.4-stable #17 Tainted: G            E
[    4.319352] -----------------------------
[    4.319354] net/ipv4/ipmr.c:1757 RCU-list traversed in non-reader section!!

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
 net/ipv4/ipmr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 6e68def66822..99c864eb6e34 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -110,7 +110,8 @@ static void ipmr_expire_process(struct timer_list *t);
 
 #ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
 #define ipmr_for_each_table(mrt, net) \
-	list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list)
+	list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
+				lockdep_rtnl_is_held())
 
 static struct mr_table *ipmr_mr_table_iter(struct net *net,
 					   struct mr_table *mrt)
-- 
2.24.1


^ permalink raw reply	[flat|nested] 4+ messages in thread

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Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2020-02-22  6:38 [PATCH 1/2] ipmr: Fix RCU list debugging warning Amol Grover
2020-02-22  6:38 ` [PATCH 2/2] ipmr: Add lockdep expression to ipmr_for_each_table macro Amol Grover
2020-02-24 21:18   ` David Miller
2020-02-25 13:10     ` Amol Grover

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